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New and unique U.S. magnetic database is forthcoming

U.S. Geological Survey, Menlo Park, California, U.S.

William Hinze

Purdue University, West Lafayette, Indiana, U.S.

G. Randy Keller

University of Texas at El Paso, U.S.

Victor Labson

U.S. Geological Survey, Denver, Colorado, U.S.

Walter Roest

Geological Survey of Canada, Ottawa, Ontario, Canada

Corresponding author: tom@usgs.gov

The first 20% of the full text of this article appears below.

An exciting and cost-effective opportunity to acquire a new U.S. magnetic anomaly database exists in calendar year 2004. High Altitude Mapping Missions Incorporated (HAMM) is currently planning an airborne mission to collect high-resolution Interferometric Synthetic Aperture Radar (IFSAR) imagery at an altitude of about 15 km, with a flight-line spacing of about 14 km over the conterminous United States and Alaska. Total and vector magnetic field data will also be collected as a secondary mission objective (i.e., a "piggy-back" magnetometer system). Because HAMM would fund the main flight costs of the mission, the geomagnetic community would acquire invaluable magnetic data at a nominal cost. These unique data should provide new insights on fundamental tectonic and thermal processes and give a new view of the structural and lithologic framework of continental areas and offshore regions.

Of particular importance is that the high-altitude magnetic data will provide a reference field to properly level the U.S. low-altitude aeromagnetic data. A recent ambitious effort to upgrade the low-altitude aeromagnetic database (NAMAG, 2002) has led to a data resource that is fundamental to geoscience investigations. However, this database, representing hundreds of millions of dollars, was constructed from a patchwork of more than 1000 airborne and shipborne surveys acquired over a period of about 50 years to address a wide variety of objectives. Significant mismatches exist between many survey data sets, some exceeding several hundred nanoTesla (one or two orders of magnitude greater than the amplitudes of magnetic anomalies caused by some sources of interest). A consistent datum for all aeromagnetic surveys will improve both qualitative and quantitative interpretations (e.g., for geologic mapping, particularly where magnetic maps are used to extrapolate observations from outcrop to covered regions, and for quantitative comparisons of magnetic properties of rock units in . . . [Full Text of this Article]